1. Field of the Invention
The present invention relates to a cable connection structure in an electric vehicle to connect cables flowing power from a battery to a device in the vehicle.
2. Description of the Related Art
A general electric vehicle supplies electric power from a battery to the driving motor of the vehicle through cables (e.g., see Patent Reference 1).
[Patent Reference 1] Japanese Patent Application Laid-Open (KOKAI) No. HEI 8-48164
Here, description will now be made in relation to the schematic configuration around the driving motor of an electric vehicle obtained through the creation of the present invention with reference to accompanying drawing FIG. 9, which is a perspective diagram schematically illustrating an electric vehicle seen from the behind.
As shown in FIG. 9, electric vehicle (vehicle) 100 includes driving motor 101 for driving vehicle 100, MCU (Motor Control Unit) 102 incorporating an inverter and a controller (both not shown) and DC/DC converter 103 accommodating an charger (not shown).
Driving motor 101 is arranged on the rear axle, and MCU 102 is disposed above driving motor 101. DC/DC converter 103 is arranged contiguously to the left side of MCU 102.
Driving motor 101, MCU 102, and DC/DC converter 103 are fixed to motor mounting frame 104 via a non-illustrated bracket or the like. The motor mounting frame 104 is fixed to a non-illustrated cross member of vehicle 100.
Further, a battery (not shown) charged with electric power to drive vehicle 100 is arranged under the floor (not shown) of vehicle 100 and forward MCU 102.
Driving motor 101 and the battery are electrically interconnected to MCU 102 by a number of cables 106, through which direct current is supplied from the battery to MCU 102 and through which cables the three-phase alternating current obtained by an inverter in MCU 102 converting the direct current into three-phase alternating current is supplied to driving motor 101.
The reference number 105 represents the driving mechanism which is a driveline for transmitting driving force generated by driving motor 101 to non-illustrated driving wheels and which is formed by a differential gear, various shafts, and other elements (all not shown). The driving mechanism is connected to driving motor 101 operable to transmit driving force to driving motor 101.
Here, the configuration of the connection between cables 106 and MCU 102 will now be detailed. As shown in FIG. 10, a terminal connector unit 102A is formed on MCU 102 to be connected to terminals 106A of cables 106 which connects MCU 102 to motor 101 and battery arranged below. Terminal connector unit 102A is formed by a cantilever horizontally projecting from the upper side of MCU main body 102B.
Inside the MCU 102, busbars 102C are installed to electrically connect cables 106 and MCU main body 102B. A bolt hole with a thread corresponding to bolt 113 is formed on the end of each busbar 102C.
Cables 106 are inserted into MCU 102 through flange 111 from the bottom of terminal connector unit 102A. Flange 111 is crimped onto against the bottom of terminal connector unit 102A by bolt 112. That avoids water immersion into the inside of MCU 102 through insertion sections of cables 106.
One end of each cable 106 takes the form of a so-called round terminal, and each terminal 106A is formed into a round ring shape through which bolt 113 penetrates. Terminal 106A of cables 106 and corresponding busbar 102C are engaged by bolt 113 in the machine direction of vehicle to thereby electrically connect MCU 102 and cables 106. On the rearface of terminal connector unit 102A, closable working window 114 is formed to allow an operator to fasten bolt 113.
If the layout design restricts driving motor 101 and battery to being arranged below MCU 102 like vehicle 100, cables 106 are preferably distributed to be connected to MCU 102 (specifically terminal connector unit 102A) from the bottom of MCU 102 so that the lengths of cables 106 becomes the shortest.
MCU 102 should be removed from vehicle 100 as shown in FIG. 11 when in vehicle 100 described with reference to FIGS. 9 and 10, maintenance of units such as motor 101 arranged under MCU 102 is to be performed. MCU 102 should be detached from vehicle 100 in the event of maintenance of MCU 102 itself.
If MCU 102 is disposed under floor (here, a trunk floor) 120 of vehicle 100, the operator temporarily lifts MCU 102 to a position (i.e., the position at which bolts 113 becomes higher than floor 120) which allows the operator to disengaging cable 106 through working window 114 to remove MCU 102 from vehicle 100 through floor opening 120A formed on floor 120 because busbars 102C are engaged to cables 106 by bolts 113 along the machine direction. Further, the operator needs to unfasten bolts 113 inside the MCU 102 being lifted. For this reason, vehicles of a type exemplified by vehicle 100 makes the maintenance of MCU 102 and other elements under MCU 102 complex.
In addition, MCU 102 should be lifted to a position at which the operator can deal with MCU 102 through working window 114. That has required an adequate ample length of each cable 106, but has been causes of cost raise and weight increase.
Cables 106 used in an above electric vehicle 100 have large diameters and high stiffness and therefore tend not to elastically deform with ease. For this reason, even if cables 106 have adequate ample length, the elasticity of the ample length applies upwardly heaving force to MCU 102, which force unnecessarily loads on terminals 106A in a normal installation state. Conversely, if ample lengths of cables 106 are set to be shorter, the stiffness of the cables 106 further greatly loads on lifting of MCU 102, lowering the operational efficiency.
These problems arise not only in connection of cables 106 and MCU 102 but also in connection of any electric machinery for any usage purpose.
The detaching direction of an electric machinery is not limited to vertical direction, and the same problems arises in the case where cables are connected in a different direction from a detaching direction.